In a natural Borrelia burgdorferi infection, spirochetes are inoculated into the mammalian host skin by salivating ticks during their blood meal. Polymorphonuclear leukocytes (PMN) accumulate at the inflammatory center of the skin lesion, while free spirochetes are often seen at the periphery. Tick saliva may promote the survival of infecting spirochetes by inhibiting PMN functions. We will examine the inhibitory effects of saliva in the mouse model of Lyme borreliosis by infecting animals via syringe with B. burgdorferi either alone or with saliva, or via infected tick. We will evaluate the effect of salvia on spirochete dissemination using real time PCR to quantify the number of spirochetes both in blood and arriving at a distal skin site. By microscopic analysis of skin, we will determine the recruitment of MIN to the inoculation site and the expression level of key functional markers on cells at eh site. In addition, we will survey the chemokines expressed in the skin first in vitro via array analysis, using relevant cells in culture stimulated with spirochetes in the presence and absence of saliva, and subsequently in infected skin in situ. These preliminary studies will be extended the future with a more detailed time course and with doses of saliva, purified components of saliva, and recombinant salivary proteins.